CVE-2026-44687
CVE-2026-44687 · Off-by-one error in 'harden-below-nxdomain' logic can shadow a stub/forward zone by a legitimate parent's NXDOMAIN
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In NLnet Labs Unbound 1.13.2 up to and including 1.25.1, stub or forward zones where the name is below an intermediate labed below a DNSSEC signed zone could be shadowed by the intermediate label's secure NXDOMAIN answer from the parent. This is caused by an off-by-one error in 'harden-below-nxdomain' logic; enabled by default. It effectively bypasses the configuration and the configured stub/forward zone is never contacted. 'harden-below-nxdomain' does an upward DNS cache walk together with a delegation point guard that does not allow NXDOMAIN synthesis above stub/forward zones. The guard tests the domain name but before stripping a label. This results in an iteration where the domain name equals the configured stub/forward zone apex that passes the guard, strips one more label, and probes the cache at the apex's immediate public parent. If that parent has a cached DNSSEC-secure NXDOMAIN, which it will for any private namespace nested two or more labels under a signed public name, the walk returns it and the configured stub/forward upstream is never contacted. This can only be triggered by the query for the intermediate label (between the stub/forward apex and the DNSSEC parent zone).
CVSS 3.7 · Niedrig · EPSS 0,2% · Korrektur verfügbar
- Veröffentlicht
- Aktualisiert
Technologie-Stack: system
Betroffene Produkte und Versionen
unbound
- Softwareversionen
- ≥ 1.13.2, < 1.25.2: Betroffen (semver)
Auf 1.25.2 aktualisieren
unbound Debian:12
- Softwareversionen
- 1.17.1-2
- 1.17.1-2+deb12u1
- 1.17.1-2+deb12u2
- 1.17.1-2+deb12u3
- 1.17.1-2+deb12u4
- 1.17.1-2+loong64
- 1.18.0-1
- 1.18.0-2
- 1.19.1-1
- 1.19.2-1
- 1.20.0-1
- 1.21.1-1
- 1.22.0-1
- 1.22.0-2
- 1.23.1-1
- 1.24.0-1
- 1.24.0-2
- 1.24.1-1
- 1.24.1-2
- 1.24.2-1
- 1.25.0-1
- 1.25.1-1
- 1.25.2-1
- 1.26.0-1
- 1.26.0-2
- 1.26.1-1
- 1.26.2-1
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Debian:13
- Softwareversionen
- 1.22.0-2
- 1.22.0-2+deb13u1
- 1.22.0-2+deb13u2
- 1.22.0-2+deb13u3
- 1.23.1-1
- 1.24.0-1
- 1.24.0-2
- 1.24.1-1
- 1.24.1-2
- 1.24.2-1
- 1.25.0-1
- 1.25.1-1
- 1.25.2-1
- 1.26.0-1
- 1.26.0-2
- Betroffene Versionsbereiche
- ECOSYSTEM: < 1.26.1-0+deb13u1
Auf 1.26.1-0+deb13u1 aktualisieren
unbound Debian:14
- Softwareversionen
- 1.22.0-2
- 1.23.1-1
- 1.24.0-1
- 1.24.0-2
- 1.24.1-1
- 1.24.1-2
- 1.24.2-1
- 1.25.0-1
- 1.25.1-1
- Betroffene Versionsbereiche
- ECOSYSTEM: < 1.25.2-1
Auf 1.25.2-1 aktualisieren
unbound Ubuntu:Pro:14.04:LTS
- Softwareversionen
- 1.4.20-1
- 1.4.21-1
- 1.4.21-1ubuntu1
- 1.4.21-1ubuntu2
- 1.4.22-1ubuntu1
- 1.4.22-1ubuntu2
- 1.4.22-1ubuntu3
- 1.4.22-1ubuntu4
- 1.4.22-1ubuntu4.14.04.1
- 1.4.22-1ubuntu4.14.04.2
- 1.4.22-1ubuntu4.14.04.3
- 1.4.22-1ubuntu4.14.04.3+esm1
- 1.4.22-1ubuntu4.14.04.3+esm2
- 1.4.22-1ubuntu4.14.04.3+esm3
- 1.4.22-1ubuntu4.14.04.3+esm4
- 1.4.22-1ubuntu4.14.04.3+esm5
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Ubuntu:Pro:16.04:LTS
- Softwareversionen
- 1.4.22-1ubuntu6
- 1.5.7-1ubuntu1
- 1.5.7-1ubuntu2
- 1.5.8-1ubuntu1
- 1.5.8-1ubuntu1.1
- 1.5.8-1ubuntu1.1+esm1
- 1.5.8-1ubuntu1.1+esm2
- 1.5.8-1ubuntu1.1+esm3
- 1.5.8-1ubuntu1.1+esm4
- 1.5.8-1ubuntu1.1+esm5
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Ubuntu:Pro:18.04:LTS
- Softwareversionen
- 1.6.5-1
- 1.6.7-1
- 1.6.7-1build1
- 1.6.7-1ubuntu1
- 1.6.7-1ubuntu2
- 1.6.7-1ubuntu2.1
- 1.6.7-1ubuntu2.2
- 1.6.7-1ubuntu2.3
- 1.6.7-1ubuntu2.4
- 1.6.7-1ubuntu2.5
- 1.6.7-1ubuntu2.6
- 1.6.7-1ubuntu2.6+esm2
- 1.6.7-1ubuntu2.6+esm3
- 1.6.7-1ubuntu2.6+esm4
- 1.6.7-1ubuntu2.6+esm5
- 1.6.7-1ubuntu2.6+esm6
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Ubuntu:Pro:20.04:LTS
- Softwareversionen
- 1.9.0-2ubuntu1
- 1.9.0-2ubuntu2
- 1.9.4-2
- 1.9.4-2ubuntu1
- 1.9.4-2ubuntu1.1
- 1.9.4-2ubuntu1.2
- 1.9.4-2ubuntu1.3
- 1.9.4-2ubuntu1.4
- 1.9.4-2ubuntu1.5
- 1.9.4-2ubuntu1.6
- 1.9.4-2ubuntu1.8
- 1.9.4-2ubuntu1.9
- 1.9.4-2ubuntu1.11
- 1.9.4-2ubuntu1.11+esm1
- 1.9.4-2ubuntu1.11+esm2
- 1.9.4-2ubuntu1.11+esm3
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Ubuntu:22.04:LTS
- Softwareversionen
- 1.13.1-1ubuntu1
- 1.13.1-1ubuntu3
- 1.13.1-1ubuntu5
- 1.13.1-1ubuntu5.1
- 1.13.1-1ubuntu5.2
- 1.13.1-1ubuntu5.3
- 1.13.1-1ubuntu5.4
- 1.13.1-1ubuntu5.5
- 1.13.1-1ubuntu5.7
- 1.13.1-1ubuntu5.8
- 1.13.1-1ubuntu5.10
- 1.13.1-1ubuntu5.11
- 1.13.1-1ubuntu5.12
- 1.13.1-1ubuntu5.13
- 1.13.1-1ubuntu5.14
- 1.13.1-1ubuntu5.15
- 1.13.1-1ubuntu5.16
- 1.13.1-1ubuntu5.17
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Ubuntu:24.04:LTS
- Softwareversionen
- 1.17.1-2
- 1.18.0-2ubuntu1
- 1.18.0-2ubuntu2
- 1.19.1-1ubuntu1
- 1.19.2-1ubuntu1
- 1.19.2-1ubuntu3
- 1.19.2-1ubuntu3.1
- 1.19.2-1ubuntu3.2
- 1.19.2-1ubuntu3.3
- 1.19.2-1ubuntu3.4
- 1.19.2-1ubuntu3.5
- 1.19.2-1ubuntu3.6
- 1.19.2-1ubuntu3.7
- 1.19.2-1ubuntu3.8
- 1.19.2-1ubuntu3.9
- 1.19.2-1ubuntu3.10
- 1.19.2-1ubuntu3.12
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Ubuntu:26.10
- Softwareversionen
- 1.24.2-1ubuntu2
- 1.25.1-1ubuntu1
- 1.25.1-1ubuntu3
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht
unbound Ubuntu:26.04:LTS
- Softwareversionen
- 1.22.0-2ubuntu2
- 1.22.0-2ubuntu4
- 1.24.2-1ubuntu1
- 1.24.2-1ubuntu2
- 1.24.2-1ubuntu2.1
- 1.24.2-1ubuntu2.2
- 1.24.2-1ubuntu2.3
- 1.24.2-1ubuntu2.4
- Betroffene Versionsbereiche
- ECOSYSTEM: (−∞, +∞)
Keine Korrektur veröffentlicht